1. Field of the Invention
The present invention relates to a high-pressure hydrogen producing apparatus.
2. Discussion of the Background
Generally, hydrogen is used as a fuel gas for power generating reactions in fuel cells. The hydrogen is generated, for example, by a water electrolysis apparatus. For decomposing water to generate hydrogen (and oxygen), the water electrolysis apparatus uses a solid polymer electrolyte membrane (ion-exchange membrane). The solid polymer electrolyte membrane is provided with electrode catalyst layers on both sides thereof to form an electrolyte membrane-electrode assembly, which is provided with current collectors on both sides thereof to form a unit cell.
A cell unit is formed by stacking a plurality of unit cells. A voltage is applied to both ends of the cell unit in the stacking direction while water is supplied to each current collector on the anode side. Thus, on the anode side of the electrolyte membrane-electrode assembly, the water is split to form hydrogen ions (protons), which pass through the solid polymer electrolyte membrane to the cathode side to combine with electrons to generate hydrogen. On the anode side, oxygen produced together with hydrogen ions is discharged with excess water from the cell unit.
As a facility of this type, a clamping apparatus in a solid polymer water electrolysis cell disclosed in Japanese Unexamined Patent Application Publication No. 2003-160891 is known. As illustrated in FIG. 5, a clamping apparatus 1 uniformly clamps a combination of an anode main electrode 2a, a plurality of unit cells 3, and a cathode main electrode 2b with a flange 4 on one side and a compression mechanism 5 on the other side.
The compression mechanism 5 includes a cylinder 6 having an inlet nozzle 6a and an outlet nozzle 6b for compression fluid, and a piston 8 disposed inside the cylinder 6 with O-rings 7 therebetween.
Japanese Unexamined Patent Application Publication No. 2003-160891 states that when the solid polymer water electrolysis cell is operated under any operating pressure or when the operating pressure is desired to be changed to any value, it is possible to carry out the operation under constant relative clamping pressure and easily achieve stable electrolysis performance regardless of the operating pressure or the change in pressure.